There exist many ways to process metals for commercial use. One example of a processed metal is Tinplate, or terneplate. Terneplate is used for many products such as soup cans, coffee containers, cookie tins, or soda cans to name a few examples. The tinplate is formed into sheets and these sheets are processed by sheet handling machines. The machines for handling terneplate are large and used for, among other things, coating the terneplate with decorative graphics often seen on soup cans or coffee tins. Throughout this processing the sheets are manipulated, or manhandled, and subjected to varying degrees of force, thrusts, twists, turns, torques and the like. Wickets are used in these machines to facilitate handling the sheets.
A wicket is grated and looks like a gate. They are used in the tin sheet coating industry and are often located within wicket ovens. Wickets are used to support sheets of material, usually tin sheets, as they are being processed to make product, the process of drying a painted tin sheet for instance. Aside from being used for supporting metal sheets, wickets are also used to manipulate metals, for example by supporting the tin sheet in a substantially vertical position along a moving conveyor. One other way the sheets are manipulated is by being slid onto and off of the wickets during processing, and for placing dried coated sheets onto a cutting machine, for instance. Wickets are well known and used in many industries, one such industry is a sheet printing operation as depicted in FIG. 5. Because wickets are generally made from a heavy metal, a wicket often scratches the tin during processing.
As is evident from the foregoing, several problems can occur when metals, such as tin sheets, are manhandled with processing machines, particularly those machines using wickets or the like. Tin, or the like, is a soft metal and prone to being scratched. Decorative graphics or other coatings applied to the metal can be ruined by rubbing, smudging or scratching for example. This problem renders the metal unusable for commercial purposes and the metal must then be reprocessed or thrown away.
In the United States alone millions of metal sheets are scratched from contact with wickets. Entire skids of tinplate are scrapped or must be hand sorted to remove the damaged sheets. A skid of tinplate has 1500-1800 sheets when delivered. Some end users will scrap the entire pallet of tin plate and send them back to the coating supplier if they even find a single scratched sheet, this can cost millions of dollars. To date, there is no easily installable solution to help this situation.
Information relevant to attempts to address these problems can be found in U.S. Pat. No. 2,406,000 (Dawn). However, this reference suffers from one or more of the following disadvantages: 1) difficult to install, 2) expensive to implement, 3) ineffective in protecting the metal from scratching during processing. Nothing mentioned in this Background section is admitted to be prior art with respect to the present invention.
For the foregoing reasons, there is a need in the industry for an apparatus that is easy and inexpensive to install and minimizes the friction between wickets and metal thereby preventing damage to the metal from the handling done by wickets.